I just bought a new Penryn MacBook (white, midlevel) from my local Apple store. It has a noticeable steady buzz that does not vary with increased or decreased usage. It reminds me of the buzzing of the florescent lights at my old college library, but it's not as loud as the lights. Also, when I lift the screen to wake up the MB from sleep mode, there is an audible grinding for a few seconds. Is the HD on the fritz out of the box? Thanks for your help.